a(n) = lcm(sigma(n), phi(n)).

Terms

a(0) =1a(1) =3a(2) =4a(3) =14a(4) =12a(5) =12a(6) =24a(7) =60a(8) =78a(9) =36a(10) =60a(11) =28a(12) =84a(13) =24a(14) =24a(15) =248a(16) =144a(17) =78a(18) =180a(19) =168a(20) =96a(21) =180a(22) =264a(23) =120a(24) =620a(25) =84a(26) =360a(27) =168a(28) =420a(29) =72